TM 1-1510-225-10 2-62 (3)   When  shutting  down  the  engines,  wait until  the  gas  generator  speeds  of  both  engines  drop below 10% prior to turning off the master switch. (4)   During aircraft operation, the ETM monitors and records data on the engine and airframe parameters and notifies maintenance personnel when the     established     limits     of     those     parameters     are exceeded.    This  data  is,  in  turn,  used  for  later  trend analysis.  The ETM has a secure feature that prevents unauthorized  changes  to  the  retained  statistical  data being recorded. Section IV.  FUEL SYSTEM 2-32.  FUEL SUPPLY SYSTEM. The   engine   fuel   supply   system,   Figure   2-18, consists of two separate but identical systems sharing a  common  fuel  management  panel,  Figure  2-19, and fuel  crossfeed  plumbing,  Figure 2-20.  Each main fuel system consists of five interconnected wing tanks and a nacelle tank.  Each auxiliary fuel system consists of one    tank    located    between    the    nacelle    and    the fuselage.    A  fuel  transfer  pump  is  located  within  each auxiliary tank.  Additionally, the system has an engine- driven boost pump, a standby fuel pump located within each nacelle tank, a fuel heater (engine oil-to-fuel heat exchanger unit), a tank vent system, tank vent heating system,    and    interconnecting    wiring    and    plumbing.   Total fuel tank capacity is shown in Table 2-2.  Gravity feed fuel flow is shown in Figure 2-21. a.   Fuel Tanks.   The main wing tanks consist of two leading edge tanks, two box section bladder tanks, and  an  integral  (wet  cell)  tank  all  interconnected  to flow  into  the  nacelle  tank  by  gravity.    This  system  of tanks is filled from the filler located near the wing tip.   The auxiliary fuel system consists of a center section tank,  located  in  the  inboard  wing,  with  its  own  filler opening   and   an   automatic   fuel   transfer   system   to transfer  the  fuel  into  the  nacelle  tank.    An  anti-siphon valve  is  installed  at  each  filler  port  to  prevent  loss  of fuel  or  collapse  of  a  fuel  cell  bladder  in  the  event  of improper securing or loss of the filler cap.  The nacelle tank is located directly behind the engine and contains a submerged, electrically operated standby fuel pump.   The  fuel  from  the  nacelle  tank  is  fed  directly  into  the engine  by  either  the  engine-driven primary fuel pump or, as backup, the standby fuel pump.  The quantity of fuel for the tanks is detailed in Table 2-3. b.  Engine-Driven Boost Pumps.  A gear-driven boost  pump  mounted  on  each  engine,  supplies  fuel, under pressure, from the nacelle tank to  the inlet of the engine-driven  primary  high-pressure  pump  for  engine starting  and  all  normal  operations.    Either  the  engine- driven boost pump or electric standby pump is capable of  supplying  sufficient  pressure  to  the  engine-driven primary     high-pressure     pump,     maintaining     normal engine operation. CAUTION Engine   operation   using   only   the   engine- driven  primary  (high-pressure)  fuel  pump without    standby    pump    or    engine-driven boost  pump  fuel  pressure  is  limited  to  10 cumulative hours.  NOTE This  condition  is  indicated by illumination of  both  the  L  or  R  FUEL  PRESS  warning annunciator and the simultaneous illumination   of   both   MASTER   WARNING annunciators.      All   time   in   this   category shall be entered on DA Form 2408-13-1  for the attention of maintenance personnel. c.   Standby     Fuel     Pumps.           A     submerged, electrically operated standby fuel pump, located within each  nacelle  tank,  serves  as  a  backup  unit  for  the engine-driven  boost  pump.    The  standby  pumps  are switched   off   during   normal   system   operations.      A standby  fuel  pump  will  be  operated  during  crossfeed operation  to  pump  fuel  from  one  nacelle  tank  to  the opposite   engine.      Each   standby   fuel   pump   has   an inertia  switch  included  in  the  power  supply  circuit.   When subjected to a 5 to 6 G shock loading, as in a crash situation, the inertia switch will remove electrical power from the standby fuel pumps.  The standby fuel pumps     are     protected     by     two     10-ampere     circuit breakers,    placarded    LEFT    or    RIGHT    STANDBY PUMP,   located   on   the   left   sidewall   circuit   breaker panel, and four 5-ampere circuit breakers (two each in parallel) on the hot battery bus.